syzbot


INFO: task hung in hub_event (3)

Status: upstream: reported on 2025/04/04 18:12
Reported-by: syzbot+40b37262be3f57b669cd@syzkaller.appspotmail.com
First crash: 63d, last: 60d
Similar bugs (10)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in hub_event usb 19 2071d 2247d 0/28 auto-closed as invalid on 2020/01/02 20:34
linux-4.14 INFO: task hung in hub_event 5 1243d 1265d 0/1 auto-closed as invalid on 2022/05/10 10:19
linux-5.15 INFO: task hung in hub_event (4) 3 43d 57d 0/3 upstream: reported on 2025/04/10 12:17
linux-6.1 INFO: task hung in hub_event (2) 1 625d 625d 0/3 auto-obsoleted due to no activity on 2023/12/29 05:51
upstream INFO: task hung in hub_event (2) usb 27 1242d 1287d 0/28 closed as invalid on 2022/02/08 09:40
linux-5.15 INFO: task hung in hub_event (2) 1 531d 531d 0/3 auto-obsoleted due to no activity on 2024/04/01 17:35
upstream INFO: task hung in hub_event (3) usb 394 19h38m 873d 0/28 upstream: reported on 2023/01/14 20:19
linux-5.15 INFO: task hung in hub_event (3) 1 320d 320d 0/3 auto-obsoleted due to no activity on 2024/10/29 18:51
linux-5.15 INFO: task hung in hub_event 3 642d 806d 0/3 auto-obsoleted due to no activity on 2023/12/12 00:26
linux-6.1 INFO: task hung in hub_event 2 788d 817d 0/3 auto-obsoleted due to no activity on 2023/08/08 09:24

Sample crash report:
INFO: task kworker/1:1:13505 blocked for more than 143 seconds.
      Not tainted 6.1.133-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:1     state:D stack:23840 pid:13505 ppid:2      flags:0x00004000
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6561
 schedule+0xbf/0x180 kernel/sched/core.c:6637
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6696
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x6b9/0xd80 kernel/locking/mutex.c:747
 hub_port_connect drivers/usb/core/hub.c:5386 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5629 [inline]
 port_event drivers/usb/core/hub.c:5785 [inline]
 hub_event+0x249e/0x5730 drivers/usb/core/hub.c:5867
 process_one_work+0x917/0x1260 kernel/workqueue.c:2292
 worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8d32e910 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8d32f110 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/27:
 #0: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6510
4 locks held by kworker/u4:4/56:
 #0: ffff8880b8e3a998 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xa8/0x140 kernel/sched/core.c:545
 #1: ffff8880b8e27788 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x419/0x790 kernel/sched/psi.c:999
 #2: ffff8880b8e28358 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x120/0x260 kernel/time/timer.c:999
 #3: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #3: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #3: ffffffff8d32e740 (rcu_read_lock){....}-{1:2}, at: ieee80211_sta_active_ibss+0xb1/0x310 net/mac80211/ibss.c:654
1 lock held by dhcpcd/3916:
 #0: ffffffff8e550c68 (rtnl_mutex){+.+.}-{3:3}, at: __netlink_dump_start+0x136/0x6d0 net/netlink/af_netlink.c:2287
2 locks held by getty/4008:
 #0: ffff88807e170098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000325e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x54a/0x1620 drivers/tty/n_tty.c:2198
5 locks held by kworker/0:7/4298:
 #0: ffff88801c6d1d38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #1: ffffc90004247d20 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #2: ffff888029224190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:837 [inline]
 #2: ffff888029224190 (&dev->mutex){....}-{3:3}, at: hub_event+0x1fe/0x5730 drivers/usb/core/hub.c:5813
 #3: ffff888146f004f8 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3172 [inline]
 #3: ffff888146f004f8 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5385 [inline]
 #3: ffff888146f004f8 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5629 [inline]
 #3: ffff888146f004f8 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5785 [inline]
 #3: ffff888146f004f8 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x2471/0x5730 drivers/usb/core/hub.c:5867
 #4: ffff888028fe6368 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5386 [inline]
 #4: ffff888028fe6368 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5629 [inline]
 #4: ffff888028fe6368 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5785 [inline]
 #4: ffff888028fe6368 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_event+0x249e/0x5730 drivers/usb/core/hub.c:5867
3 locks held by kworker/u4:5/4303:
 #0: ffff888017c79138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #1: ffffc90004297d20 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #2: ffffffff8e550c68 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:263
5 locks held by kworker/u4:25/13059:
 #0: ffff888017e16938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #1: ffffc90003a07d20 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #2: ffffffff8e544110 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0x166/0xd20 net/core/net_namespace.c:594
 #3: ffffffff8e550c68 (rtnl_mutex){+.+.}-{3:3}, at: default_device_exit_batch+0xe5/0xa20 net/core/dev.c:11477
 #4: ffffffff8d333d78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:323 [inline]
 #4: ffffffff8d333d78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x360/0x930 kernel/rcu/tree_exp.h:962
5 locks held by kworker/1:1/13505:
 #0: ffff88801c6d1d38 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #1: ffffc9000520fd20 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #2: ffff888146f0b190 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:837 [inline]
 #2: ffff888146f0b190 (&dev->mutex){....}-{3:3}, at: hub_event+0x1fe/0x5730 drivers/usb/core/hub.c:5813
 #3: ffff888146f0e4f8 (&port_dev->status_lock){+.+.}-{3:3}, at: usb_lock_port drivers/usb/core/hub.c:3172 [inline]
 #3: ffff888146f0e4f8 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5385 [inline]
 #3: ffff888146f0e4f8 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5629 [inline]
 #3: ffff888146f0e4f8 (&port_dev->status_lock){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5785 [inline]
 #3: ffff888146f0e4f8 (&port_dev->status_lock){+.+.}-{3:3}, at: hub_event+0x2471/0x5730 drivers/usb/core/hub.c:5867
 #4: ffff888028fe6368 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect drivers/usb/core/hub.c:5386 [inline]
 #4: ffff888028fe6368 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_port_connect_change drivers/usb/core/hub.c:5629 [inline]
 #4: ffff888028fe6368 (hcd->address0_mutex){+.+.}-{3:3}, at: port_event drivers/usb/core/hub.c:5785 [inline]
 #4: ffff888028fe6368 (hcd->address0_mutex){+.+.}-{3:3}, at: hub_event+0x249e/0x5730 drivers/usb/core/hub.c:5867
3 locks held by kworker/1:3/13999:
 #0: ffff888017c70938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #1: ffffc900035f7d20 (deferred_process_work){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #2: ffffffff8e550c68 (rtnl_mutex){+.+.}-{3:3}, at: switchdev_deferred_process_work+0xa/0x20 net/switchdev/switchdev.c:104
2 locks held by kworker/0:8/16483:
 #0: ffff888017c72138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
 #1: ffffc90004a6fd20 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x806/0x1260 kernel/workqueue.c:2267
1 lock held by syz.9.2688/16701:
 #0: ffffffff8d333d78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:323 [inline]
 #0: ffffffff8d333d78 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x360/0x930 kernel/rcu/tree_exp.h:962
7 locks held by syz-executor/17052:
 #0: ffff88807e2dc460 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x269/0xbc0 fs/read_write.c:580
 #1: ffff88805648c488 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1e7/0x4f0 fs/kernfs/file.c:325
 #2: ffff8880269c82c0 (kn->active#50){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x20b/0x4f0 fs/kernfs/file.c:326
 #3: ffffffff8de61ae8 (nsim_bus_dev_list_lock){+.+.}-{3:3}, at: del_device_store+0xf8/0x480 drivers/net/netdevsim/bus.c:209
 #4: ffff8880576150e8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:837 [inline]
 #4: ffff8880576150e8 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1080 [inline]
 #4: ffff8880576150e8 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xb6/0x880 drivers/base/dd.c:1283
 #5: ffff8880576162f8 (&devlink->lock_key#5){+.+.}-{3:3}, at: nsim_drv_remove+0x54/0x160 drivers/net/netdevsim/dev.c:1677
 #6: ffffffff8e550c68 (rtnl_mutex){+.+.}-{3:3}, at: netdev_wait_allrefs_any net/core/dev.c:10370 [inline]
 #6: ffffffff8e550c68 (rtnl_mutex){+.+.}-{3:3}, at: netdev_run_todo+0x74c/0xf20 net/core/dev.c:10489

=============================================

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted 6.1.133-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 nmi_cpu_backtrace+0x4e1/0x560 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1ca/0x430 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xf88/0xfd0 kernel/hung_task.c:377
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 56 Comm: kworker/u4:4 Not tainted 6.1.133-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: bat_events batadv_nc_worker
RIP: 0010:trace_lock_release include/trace/events/lock.h:69 [inline]
RIP: 0010:lock_release+0xcf/0xa20 kernel/locking/lockdep.c:5673
Code: 0d 0f 86 c2 05 00 00 89 db 48 89 d8 48 c1 e8 06 48 8d 3c c5 a8 bb a0 8e be 08 00 00 00 e8 69 31 77 00 48 0f a3 1d e9 df 35 0d <73> 0d e8 5a bb 08 00 84 c0 0f 84 c5 05 00 00 48 c7 c0 74 f0 a0 8e
RSP: 0018:ffffc90001577a40 EFLAGS: 00000257
RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffffffff816adbb7
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8ea0bba8
RBP: ffffc90001577b78 R08: dffffc0000000000 R09: fffffbfff1d41776
R10: 0000000000000000 R11: dffffc0000000001 R12: 1ffff920002aef54
R13: ffffffff8a82a495 R14: ffff88807d646148 R15: dffffc0000000000
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffcef4a6d18 CR3: 000000000d08e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 rcu_lock_release include/linux/rcupdate.h:355 [inline]
 rcu_read_unlock include/linux/rcupdate.h:824 [inline]
 batadv_nc_process_nc_paths+0x2f0/0x390 net/batman-adv/network-coding.c:699
 batadv_nc_worker+0x426/0x610 net/batman-adv/network-coding.c:728
 process_one_work+0x917/0x1260 kernel/workqueue.c:2292
 worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/04/07 18:44 linux-6.1.y 3dfebb87d7eb a2ada0e7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in hub_event
2025/04/04 18:29 linux-6.1.y 8e60a714ba3b 1c4febdb .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in hub_event
2025/04/04 18:27 linux-6.1.y 8e60a714ba3b 1c4febdb .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in hub_event
2025/04/04 18:27 linux-6.1.y 8e60a714ba3b 1c4febdb .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in hub_event
2025/04/04 18:21 linux-6.1.y 8e60a714ba3b 1c4febdb .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in hub_event
2025/04/04 18:13 linux-6.1.y 8e60a714ba3b 1c4febdb .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in hub_event
2025/04/04 18:12 linux-6.1.y 8e60a714ba3b 1c4febdb .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in hub_event
2025/04/04 18:12 linux-6.1.y 8e60a714ba3b 1c4febdb .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in hub_event
* Struck through repros no longer work on HEAD.